Image: IDVsolutions/Flickr
John Nelson of IDV Solutions graphed the map of the United States, according to the areas that have their own Craigslist board:
... here is a map that approximates geographic coverage to individual sites using a Voronoi process as a base (more info on process below). It is at least a start at visualizing the geographic coverage and distribution of the community-driven instances of craigslist.
Link [Flickr] - via Datavis | If you're curious, here's the Wikipedia article on Voronoi diagram used in the making of the map
http://www.youtube.com/watch?v=sXHc927vdhw